Hi Nanook ,
Motivation is always a topic with a difficult answer, there are lot of factors to have in mind to get to the cause of lack of motivation, and the strategies to change it depends on a good understanding of it.
The best way is to find a specialised professional, its normal to loose motivation and to not know to manage it.
Some solutions to are :
Find a goals that you would like to do, start doing the easy ones first, after a the easy ones are done, you will gain trust to reach the other.
Do the things that you love the most first , you will also gain the capacity to tackle the other things because you are happy by doing first and completed the ones you love.
I Hope I could help even with my short answer.